The present invention relates generally to cartridges for disks such as a microfloppy disk, and particularly, to the cartridges for disks which need high-speed rotation due to increased storage capacity.
Referring to FIG. 5, a known disk cartridge 101 comprises a disklike recording medium 102, a center core 103 mounted in the center thereof and made of magnetic metal, a shell 104 for rotatably accommodating the disklike recording medium 102 with the center core 103 located in an opening 104a, a pair of liners 105, 106 placed on the upper and lower inner surfaces of the shell 104, and a lifter 107/liner pressing ribs 108 for lightly pressing the liners 105, 106 to the upper and lower sides of the disklike recording medium 102.
When loading the disk cartridge 101 into a drive, a bottom plate 103a of the center core 103 is attracted on a disk table 201 of the drive by a magnet 202. And a spindle 203 of the drive enters a center hole 103b formed in the center of the bottom plate 103a of the center core 103, obtaining centering so called. The spindle 203 rotates with the disk table 201 to carry out recording/reproducing by a magnetic head of the drive which enters the shell 104 through a recording/reproducing opening, not shown, formed therein. The liners 105, 106 contact the upper and lower sides of the disklike recording medium 102 to remove dust, etc. and produce appropriate disk slide torque.
With recent development of multimedia, image and voice data are diversified, which needs increased storage capacity of microfloppy disks, resulting in requirements for high density and high-speed rotation thereof.
With the known disk cartridge 101, when rotating the disklike recording medium 102 at a speed several to several tens times as high as a conventional speed, the liners 105, 106 accelerate wear of a signal record surface of the disklike recording medium 102, deteriorating the durability thereof. Moreover, even if the liners 105, 106 are positioned so as not to directly contact the upper and lower sides of the disklike recording medium 102 upon high-speed rotation thereof, they disturb air flow or laminar flow produced on the surface of the disklike recording medium 102 by high-speed rotation, which forms turbulent flow to cause swinging of the signal record surface of the disklike recording medium 102, resulting in lowered recording/reproducing accuracy.
Referring to FIG. 6, the disk cartridge 101 with no liner is proposed to solve such inconvenience. In the operating state where the disk cartridge 101 is chucked on the disk table 201 of the drive, the upper and lower sides 102a, 102b of the disklike recording medium 102 are in non-contact with the upper and lower inner surfaces 104a, 104b of the shell 104, producing no problem. However, in the non-operating state or upon keeping and transport, the lower side 102b of the disklike recording medium 102 contacts the lower inner surface 104b of the shell 104 as shown in FIG. 7, or the upper side 102a of the disklike recording medium 102 contacts the upper inner surface 104a of the shell 14 as shown in FIG. 8 when the disk cartridge 101 is placed upside down, suffering damage easily. Note that in the latter case as shown in FIG. 8, a slight clearance .delta. is defined between the upper side of the disklike recording medium 102 and the shell 105 by a flange 103c of the center core 103, which cannot fully prevent contact between the two, however.
If the upper and lower inner surfaces 104a, 104b of the shell 104 have a flash or a mark of an ejector pin for ejecting a molding from a mold, which are formed upon plastic molding, such flash or mark may injure the upper or lower side of the disklike recording medium 102.
It is, therefore, an object of the present invention to provide disk cartridges which are free of the above inconvenience, and contribute to improvement in the durability of the disklike recording medium.